package com.emode.util;


import java.util.Random;

public class RandomStringUtils
{
  private static final Random RANDOM = new Random();

  public static String random(int count)
  {
    return random(count, false, false);
  }

  public static String randomAscii(int count)
  {
    return random(count, 32, 127, false, false);
  }

  public static String randomAlphabetic(int count)
  {
    return random(count, true, false);
  }

  public static String randomAlphanumeric(int count)
  {
    return random(count, true, true);
  }

  public static String randomNumeric(int count)
  {
    return random(count, false, true);
  }

  public static String random(int count, boolean letters, boolean numbers)
  {
    return random(count, 0, 0, letters, numbers);
  }

  public static String random(int count, int start, int end, boolean letters, boolean numbers)
  {
    return random(count, start, end, letters, numbers, null, RANDOM);
  }

  public static String random(int count, int start, int end, boolean letters, boolean numbers, char[] chars)
  {
    return random(count, start, end, letters, numbers, chars, RANDOM);
  }

  public static String random(int count, int start, int end, boolean letters, boolean numbers, char[] chars, Random random)
  {
    if (count == 0)
      return "";
    if (count < 0) {
      throw new IllegalArgumentException("Requested random string length " + count + " is less than 0.");
    }
    if ((chars != null) && (chars.length == 0)) {
      throw new IllegalArgumentException("The chars array must not be empty");
    }

    if ((start == 0) && (end == 0)) {
      if (chars != null) {
        end = chars.length;
      }
      else if ((!(letters)) && (!(numbers))) {
        end = 2147483647;
      } else {
        end = 123;
        start = 32;
      }

    }
    else if (end <= start) {
      throw new IllegalArgumentException("Parameter end (" + end + ") must be greater than start (" + start + ")");
    }

    char[] buffer = new char[count];
    int gap = end - start;

    while (count-- != 0)
    {
      char ch;
      if (chars == null)
        ch = (char)(random.nextInt(gap) + start);
      else {
        ch = chars[(random.nextInt(gap) + start)];
      }
      if (((letters) && (Character.isLetter(ch))) || ((numbers) && 
        (Character.isDigit(ch))) || (
        (!(letters)) && (!(numbers))))
      {
        if ((ch >= 56320) && (ch <= 57343))
          if (count == 0) {
            ++count;
          }
          else {
            buffer[count] = ch;
            --count;
            buffer[count] = (char)(55296 + random.nextInt(128));
          }
        else if ((ch >= 55296) && (ch <= 56191))
          if (count == 0) {
            ++count;
          }
          else {
            buffer[count] = (char)(56320 + random.nextInt(128));
            --count;
            buffer[count] = ch;
          }
        else if ((ch >= 56192) && (ch <= 56319))
        {
          ++count;
        }
        else buffer[count] = ch;
      }
      else {
        ++count;
      }
    }
    return new String(buffer);
  }

  public static String random(int count, String chars)
  {
    if (chars == null) {
      return random(count, 0, 0, false, false, null, RANDOM);
    }
    return random(count, chars.toCharArray());
  }

  public static String random(int count, char[] chars)
  {
    if (chars == null) {
      return random(count, 0, 0, false, false, null, RANDOM);
    }
    return random(count, 0, chars.length, false, false, chars, RANDOM);
  }
}
